doc: improve net.md on sockets and connections

* Improve description of socket.connect, net.connect,
  net.createConnection
* Nest the overloaded signatures
* Alias net.connect to net.createConnection
* Add type annotations to the options
* Make a separate section to explain IPC support and
  how to specify the path parameter.
* General improvements to wording and explanation

PR-URL: nodejs#11700
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>